Recently, BOE's research team published a paper titled Novel Package Design Enhances Optical Efficiency of Micro LED Displays in the journal Information Display.
Micro LED Display Microstructure Packaging Design Process (Image source: Information Display)
The study proposes an innovative Micro LED packaging scheme, successfully addressing industry technical challenges such as strong sidewall emission of micro LED chips, low light energy utilization efficiency, and color shift.
It is reported that as pixel size shrinks to below 50μm, the relative area of the chip sidewall increases, leading to enhanced lateral emission and reduced top emission of Micro LEDs. This causes brightness loss and color deviation, restricting the application of Micro LEDs in high-precision display scenarios.
To tackle this issue, BOE's research team developed a composite packaging structure consisting of high-refractive-index transparent adhesive, white high-reflective resin, microlens arrays, and patterned black matrix (BM).
By introducing a gradient refractive index layer on Micro LED chips, researchers effectively improved the exit angle of light from the top of the chip, increasing the critical angle from 25 degrees to a maximum of 65.9 degrees and significantly enhancing top light extraction efficiency.
Meanwhile, the white reflective resin forms an isosceles trapezoidal structure between chips, which can concentrate and scatter light, increasing the brightness at 0° viewing angle by approximately 27%. Additionally, a plasma process to remove residual adhesive ensures unobstructed light emission.
In terms of light control, the team used nanoimprint lithography technology to fabricate high-precision microlens arrays, achieving effective convergence of light within ±60°.
Simulation results show that when the lens curvature is 0.03 and the refractive index is 1.85, light intensity increases by over 53%. Furthermore, the study introduced a patterned black matrix into the packaging glass layer, effectively reducing reflectivity to less than 2% and achieving a high contrast ratio exceeding 20,000:1, significantly improving display quality.
(a) Micro LED structure, (b) Light emission direction inside the chip, (c) Light distribution (Image source: Information Display)
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BOE's research team stated that this scheme not only achieves breakthroughs in optical efficiency and uniformity but also considers packaging reliability. The combination of the glass cover and OCA (Optically Clear Adhesive) layer enhances waterproof, anti-oxidation, and wear-resistant properties, providing a reliable path for the mass production application of Micro LEDs in fields such as automotive displays, AR/VR headsets, and wearable devices.
BOE has not only achieved the latest Micro LED research results but also continues to promote the development of Mini/Micro LED direct display technology and applications.
Post time: Oct-23-2025